Annals of the South African MuseumThe Museum, 1991 - Natural history |
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Page 6
... restricted here , the family Trigoniidae comprises only the nominate sub- family and the Pleurotrigoniinae van Hoepen , 1929 , in which the very narrow escutcheon is unornamented , the marginal carina becomes obsolete in maturity , the ...
... restricted here , the family Trigoniidae comprises only the nominate sub- family and the Pleurotrigoniinae van Hoepen , 1929 , in which the very narrow escutcheon is unornamented , the marginal carina becomes obsolete in maturity , the ...
Page 25
... restricted to nepionic stages , marginal carina often restricted to umbonal region , anteriorly produced so that umbones are generally not subterminal , area rela- tively narrow with concentric ornament in nepionic stages later smooth ...
... restricted to nepionic stages , marginal carina often restricted to umbonal region , anteriorly produced so that umbones are generally not subterminal , area rela- tively narrow with concentric ornament in nepionic stages later smooth ...
Page 39
... restricted to the nepionic stage . The area is narrow , bipartite , with oblique costellae in the umbonal region but later smooth . The flank costae of the nepionic stages are subconcentric , with fine trans- verse ridges . Later costae ...
... restricted to the nepionic stage . The area is narrow , bipartite , with oblique costellae in the umbonal region but later smooth . The flank costae of the nepionic stages are subconcentric , with fine trans- verse ridges . Later costae ...
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Common terms and phrases
Algoa Basin Anditrigonia antecarinal sulcus anterior commissure anterolateral shoulder anteroventrally Apiotrigoniinae Bivalvia broad chevrons coarse commissure comprises convex Cooper Cretaceous Description Shell Diagnosis elongate escutcheon carina faunas finely crenulated flank costae flank ornament genus growth rugae growth striae Hauterivian Hoepen holotype inflated anteriorly interspaces Iotrigonia irregular Kobayashi kraussi Kitchin lanceolate large maximum length Lateral view lectotype left valve longitudinal groove Megatrigoniacea moderately Myophorella Myophoriidae Nakano neotype nepionic stages Neumayr nodate Nototrigoniinae opisthogyrous beaks Paranditrigonia paratypes persisting to maturity phyletic Port Elizabeth Museum posterior set posterodorsal margin Poulton Pterotrigonia radial costellae radial ornament Rennie respiratory margin Reyes ribs right valve rostrate shallowly concave shell length Skwarko smooth South African Museum Steinmanella herzogi Goldfuss straight strongly oblique subconcentric subfamily Sundays River Superfamily synonymy Tashiro Tithonian transverse costellae transverse ornament Trigonia Trigoniacea Trigoniinae trigonioid tubercles Type species Upper Valanginian V-shaped Valanginian vau Sharpe ventral margin ventricosa Krauss Yaadia